Recurring Dream. Job and come to land?

My friend just joined ship and after 15 days he started dream like he was trapped in place related to his work place and in next frame..he was on some other place and that place was his room and he woke up and checked his room as he saw room before in dream so it took 10-15 second to come to reality and he also checked his clothes that he might be sleep with his clothes..then this thing continue for 7 days initially he thought that it may be due to new work place..but it continues and its around 20-21 day he woke up around 2-3 am..daily basis..as I discuss with him..he doesn't have any stress or anxiety or depression issues..he also sleep around 10:30pm....he talked to his friends , family daily basis..so what could be the possible reason? As his work not affected but sleep was affecting ..can he continue his work or left his job and come to land?